Spinneret and method of producing the same



Dec. 6, 1938. e. M. ALLEN ET AL SPINNERET AND METHOD OF PRODUCING THE SAME Filed Jan. 7, 1937 /r/ll/l h i 6 a :II 1 J J v a 4 9 M a l M i a i a i J i i W m 1 mm w R mm I l l I l I l l I I, Y

| I I I I I l l l I INVENTORS GEORGE M. ALl 'EN GILBERT C. BARTON BY THEIR ATTORNEYS Patented Dec. 6, 1938 UNITED STATES PATENT OFFICE SPINNERET AND METHOD OF PRODUCING THE SAllIE Application January 7, 1937, Serial No. 119,488

4 Claims.

This invention relates to spinnerets and methods of producing the same, and more'particularly to spinnerets or jets adapted to be connected to a spinning pump for spinning rayon or the like 5 by squirting or extruding spinning solution through minute holes in the face of the spinneret.

In the viscose process and some other processes of spinning rayon it is necessary to have the spinneret made of a material resistant to both acids and alkalis. For this reason the spinneret up to the present time has usually been made of the noble metals. In View of the thousands of such spinnerets both in use and in stock which are necessary for the operation of a commercial rayon spinning plant, the amount of metal required represents a large capital investment. It is therefore the main object of the present invention to reduce the quantity of metal required for the construction of the spinneret.

The diameter of the face, diameter of flange, and height of spinneret are constants determined by usage.

The face of the spinneret must not only withstand the internal pressure of the spinning solution but at various times the external pressure of a mans thumb endeavoring to wipe the face clean. Further, the operator presses his thumb against the majority of the holes so as to increase the internal pressure to such an extent that the rate of flow will be in'creased,thereby dislodging any dirt particles in the free holes.

The flange of the spinneret must be of sufficient thickness to retain its corrugated contour under compression. As the seal of the spinning solution is made at this point, a thinning of the metal in this area was not deemed advisable.

The side wall of the spinneret is subject only to tension stresses of the spinning pressure. As

40 this area constitutes 60% of the total weight of the spinneret, it is therefore a particular object of this invention to reduce the thickness of the side wall of the spinneret. A further object is to increase the tensile strength of the side wall 5 by work hardening, simultaneously with the thinning, by a swaging operation.

Other objects will be apparent from the following description in connection with the accompanying drawing, in which- 50 Figure 1 is a vertical cross-section through a blank or piece of metal in the early stage of the manufacture of the spinneret, also showing in dotted lines the condition after the side walls have been thinned and lengthened by a swaging operation;

Figure 2 is a vertical cross-section through the spinneret shell according to the present invention; and

Figure 3,is a face view or end elevation illustrative'of one form of swaging machine by means 5 of which the spinneret shell may be thinned.

The spinneret according to the present invention as shown in Figure 2 comprises a single piece of noble metal formed into a cup shaped shell,

having a face 4 formed by the bottom of the 10.

cup-shape, and a side wall 5 integral therewith and extending therefrom to an annular flange 6, by means of which the spinneret may be mounted for connection to a spinning pump for spinning rayon or the like. I 15 The flange 6 is annularly corrugated to provide aleak-proof joint when mounting the spinneret, and the face 4 is ultimately tooled'to provide the extrusion orifices through which the spinning I solution is to be squirted, in the spinning process. 20

The side wall 5 is materially thinner than the remainder of the shell, being for example of about half the thickness of the face 4 and the flange 6. This thinner side wall is of increased tensile strength to compensate for the reduction to thick- 25 ness, and to take the tension stresses resulting from the pressure of the spinning pump.

The spinneret described above is manufactured by first forming a cup-shape, preferably by a pressing operation, and then thinning the side 30 wall, preferably by a swaging operation. While the thinning may be done by a spinning operation, swaging is less diificult to control than spinning. In addition either -the swaging or spinning operation work hardens the metal. The 35 swaging method being preferred, the manufacture of the spinneret is described in detail according to that method.

A plate or piece of noble metal of uniform thickness is dished or formed into a cup-shape 40 as shown in full lines in Figure 1, for example by a pressing operation. This form has a base M, an annular flange l6, and a side wall l5 therebetween. The side wall l5 in this stage is of the same thickness as the base I! and flange IE, but the length thereof constituting the depth of the cup-shape, is materially less than the depth of the finished spinneret.

For the swaging operation, the blank shown in full lines in Figure 1 is mounted on a mandrel ll having if necessary, a small taper in order to strip the shell from the mandrel. The blank on the mandrel is inserted in a swaging machine and the side wall I 5 is subjected to swaging operation, which reduces the thickness thereof to materially 35 i face of the spindle 1.

thinner than the thickness of the base II and the remainder of the shell. At the same time, the

swaging work-hardens the metal and increases the tensile strength at least compensating for the reduction in thickness.

One form of swaging machine is illustrated in Figure .3, which comprises a revolving spindle l having in its face a diametral slot 8, in which are slidably mounted a set of cooperating swaging dies 9. These diesare held between backers Ill slidable in the same groove and having rounded ends projecting beyond the periphery of the spindle.

Surrounding the spindle I is an annular rack I2 loosely containing a plurality of annularly spaced-rolls l3. The revolution of the spindle l ,dies 9 together.

causes the dies and backers to pass between successive pairs of opposing rolls 13 which force the The dies revolve rapidly around the work, which is stationary, while the rack l2 revolves very slowly, being moved only by .the slight motion of the rolls l3 during the time of contact with the backers, but which evenly dis--- tributes the effect of the dies.

The dies 9 are blocks of hardened steel which have formed on their innerfaces the impression of the shape or the diameter of the work it is desired to produce, with an enlargement or flare at the 'outer or entering end, large enough to allow the unreduced stock to enter. The dies are set up by placing shims (not shown) between the dies 9 and number of operations is undesirable. By dividing the total reduction in thickness into steps by four operation with one size of die.

operations withjfour difierent sized sets of dies, the swagingmay be accomplished, even with grain structure not of the maximumfinenesst We have constructed spinnerets, starting with a metal of a thickness of 15 mils (thousandths of an inch) and reducing the side wall to 8 mils in one swagingopera'tion using one size of swaging die, and from 8 mils to mils by a second swaging operation using a smaller size of swaging die, but

we prefer to start with a metal of 10 mils thickness, and reduce the side wall to 5 mils by one To accomplish this it is necessary that the metal be of such fine grain structure as to withstand the swaging without rupture or other failure which would increase the amount of expensive scrap.

We prefer to use an alloy of 70% gold and 30% platinum. However other proportions of these metals may be used, or alloys of. other noble metals, or even a noble metal alone. It will be understood that many other modifications may be made without departing from the spirit of the invention, within the scope of the appended claims. a

1. The method of making a shell for a spinneret for use in spinning rayon which comprises forming a cup shape member of less depth than the finished article of noble metal having an integral base portion constituted by the bottom of the cup shape for perforation to permit spinning solution to be extruded therethrough and a' side wall, and hammerswaging said side wall and thereby extending it to its finished length while thinning it and increasing .its hardness and tensile strength.

2. The methodof making a shell for a spinneret for use in spinning rayon which comprises forming .an integral cup shape member of less depth than the finished article of noble metal having a face. portion constituted by the bottom of the cup shape for perforation to permit spinning solution to be extruded therethrough, a side wall and an attachment flange, and hammer swaging said side wall and thereby extending it to its finished length while thinning said sidewall and increasing its hardness and tensile strength.

3. A shell of noble metal for a spinneret for use in spinning rayon comprising an integral face portion for perforation to permit spinning solution to be extruded therethrough and a side wall, the shell being formed from a cup shapemember of noble metal of less depth than the finished article and the side Wall of which has been hammer swaged, thereby thinning and extend:- ing it to its finished length, the side wall being thinner and of greater hardness and tensile strength than the face portion.

4. A shell of noble metal for a spinneret for use in spinning rayon comprising an integral face portion forperforation to permit spinning solution to be extruded therethrough, a side wall, and an attachment flange, the shell being formed from a cup shape member of noble metal of less depth than the finished article and the side wall of I which has been hammer swaged, thereby thinning and extending it to its finished length, the side wall being thinner and of greater hardness and tensile strength than the face portion.

GEORGE M. ALLEN. GILBERT BARTON. 

